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From: Paul Allen <nospam@ugcs.caltech.edu>
To: Michal Mertl <mime@traveller.cz>
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Cc: Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-current@freebsd.org,
	Brian Candler <B.Candler@pobox.com>
Subject: Re: vmstat's entries type
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Surely all you need to do is a cheap crit_enter,crit_exit 
while updating the 64-bit per cpu counters.  and on
a 64-bit arch you skip the crit_enter,crit_exit.

Seriously this is a bike shed.  We can summarize it thus:
statistics should be maintained in 64-bit counters, these
counters should be per-cpu and consistent in that context,
nothing else should appear on the critical path.

**end of story**

         Paul

p.s., and as a general of thumb, if a per-cpu solution
doesn't explode in complexity/memory usage it should be
preferred over a mutex by default.